1. Field of the Invention
This invention relates to a device for use in tubing expansion, and also to a method of expanding tubing. In particular, embodiments of the invention relate to devices and methods for use in expanding tubing downhole.
2. Description of the Related Art
In the oil and gas exploration and production industry, bores drilled to access subsurface hydrocarbon-bearing reservoirs are lined with tubing, known as casing and liner. Furthermore, strings of tubing may be located within the cased bore to, for example, carry production fluid to surface. Recently, there have been numerous proposals to use tubing which is expanded downhole, that is tubing of a first diameter is run into a bore and then expanded to a larger second diameter downhole. This offers many advantages to the operator, primarily providing the ability to create lined bores which do not necessarily suffer a loss in internal diameter each time a string of tubing is located in the bore, beyond an existing section of tubing-lined bore.
Early proposals for expanding tubing downhole featured the use of cones or mandrels, which are driven through the tubing in order to expand the tubing. Other proposals include the use of roller expanders, which feature radially-urged rollers. The expanders are rotated within the tubing, and create a reduction in the wall thickness of the tubing, with a corresponding increase in diameter.
It is among the objectives of embodiments of the present invention to provide improved devices and methods for use in expanding tubing downhole.